sip interface configuration with multiple ports

Hi,

 

We have IP-PBX on the access side which has one IP Address. I have defined three trunks towards the IP-PBX. In order to do this I have configured the following;

 

1. 3 different session-agents's targeting the IP Address of the IP-PBX with different ports.

2. 1 sip-interface with 3 different sip-ports.

 

          
        sip-port
                address                        10.122.217.100
                port                           5060
                transport-protocol             TCP
                tls-profile                   
                allow-anonymous                all
                ims-aka-profile        

 

sip-port
                address                        10.122.217.100
                port                           5065
                transport-protocol             TCP
                tls-profile                   
                allow-anonymous                agents-only
                ims-aka-profile               

 

sip-port
                address                        10.122.217.100
                port                           5066
                transport-protocol            TCP
                tls-profile                   
                allow-anonymous                agents-only
                ims-aka-profile          

 

When IP-PBX sends INVITE to the SBC 10.122.217.100:5066
, SBC receives it from its port 5060.  Any idea why it behaves like this?

 

Have you ever experiment such configuration that IP-PBX has one IP address and it has multiple sessions towards the SBC?